Photographic developer



Unite States Patent PHOTOGRAPHIC DEVELOPER Robert E. Fuller, Woburn, Mass.

No Drawing. Application October 28, 1954 Serial No. 465,450

7 Claims. (Cl. 96-66) This invention relates to photography, and more particularly to photographic developers of improved and advantageous characteristics.

By the present invention, there is provided an all-purpose photographic developer capable of producing negatives and prints of fine photographic quality, and yet which exhibits characteristics aifording great convenience in storage and use. Photographically, among other qualities, the developer exhibits the unique combination of properties of developing rapidly and yet producing negatives and prints of very time grain. The developer exhibits good keeping qualities, both before and after solution in water. A marked advantage for the amateur is that the developer may be made in the form of a one-part developer, either powder or tablet, and a highly advantageous feature is that the developer may be prepared in the form of a readily soluble, efiervescent powder or tablet.

The developer of this invention is characterized by the presence of sizable proportions of sodium acetate therein, for example, from about 20% to about 60% by weight of the dry solids of the developer. The pH of the developer in aqueous solution may range from about 8 to about 11, and a pH of 9 has been found highly suitable. When the developer is prepared as an effervescent powder or tablet, the sodium acetate may be incorporated in whole or in part in the form of sodium diacetate, the formula of which may be given as (CH COONa) (CH COOH) (H The sodium diacetate also provides a source of acid in.

dry form for the developer prepared as an efiervescent powder or tablet.

The developer of this invention contains other constituents conventional in developers in general. The nature of the reducing agent, or silver halide developer, is not critical, but it has been found that the use of Metol (p-methylaminophenol sulfate) and hydroquinone in combination is very effective, although the invention is not limited thereto. A preservative for the developer is preferably present, such as the commonly employed sodium sulfite. An accelerator of the developer such as sodium carbonate is usually incorporated. The sodium carbonate also provides a source of carbon dioxide for the effervescent powder or tablet. Ordinarily the use of a restrainer of the developer such as potassium bromide is not necessary, although its use is not precluded. Other types of constituents may be incorporated if desired.

The invention may be illustrated by a developer inthe form of an efiervescent tablet wherein the total sodium 2,825,647 Patented Mar- 4, 1958 a portion of the sodium carbonate incorporated therein. The composition of such developer'is as follows:

Example 1 Ounces avoirdupois In the above composition the'Metol and hydroquinone are reducing agents or the silver halide developer, the sodium sulfite is a preservative for the developer, and the sugar is a binder or tabletting agent. The sodium carbonate is an accelerator of the developer, and when the tablet is dissolved in water, a portion of the sodium carbonate reacts with the acetic acid content of the sodium diacetate to impart effervescence, as well as to form additional sodium acetate in solution. In the above composition the available sodium acetate present is slightly over 27 /2 by weight of the solids.

The tablet of this example may be prepared by compounding the Metol, hydroquinone and sodium sulfite thoroughly, and then adding the sugar together with '3 fluid ounces of water, and beating the mixture to produce a moist conglomerate. The conglomerate is then dried, for example, by heating for about 45 minutes on coils containing steam at 6 lbs. pressure. The resulting dried material is then ground to about 14-16 mesh, to produce a granular material suitable for tablet making.

The sodium diacetate and sodium carbonate are then mixed with the granular material described in the preceding paragraph. The rnixture is thoroughly drummed, for example for about 30 minutes, and then pressed into tablets. Conveniently the tablets may weigh grains each.

To form a developing solution, one 75-grain tablet may be dissolved in 8 fluid ounces of water, and the resulting solution exhibits a pH'of about 9. Due to the effervescent character of the tablet, the solution thereof takes place readily. At this concentration, ordinary film may be developed in 5 minutes at 68 F.

In Example 2, given below, there is illustrated an efiervescent tablet, similar to that of Example 1, except that a mixture of sodium acetate and sodium diacetate is employed to provide the available sodium acetate content.

Example 2 Ounces avoirdupois Metol 4.8 Hydroquinone 6.1 Anhydrous sodium sulfite 30 Sugar 3. Sodium carbonate monohydrate 33.8 Anhydrous sodium diacetate (containing approximately 40% acetic acid) 19.8 Anhydrous sodium acetate 11.

Total 108.5

In the above composition, the constituents have the same functions as described-in connection with Example 1. The sodium acetate content isprovided only in part, by sodium diacetate and the remainder is provided by sodium acetate added as such. Less sodium carbonate is employed than in the case of Example 1. In Example 2, the available sodium acetate is slightly over 31% by weight of the solids. V

The effervescent tablet of Example 2 may be prepared in the same manner as that of Example 1, the sodium acetate being added with the sodium diacetate and sodium carbonate. grains each.

Again, the resulting tablets may weigh 75 As inExample I, one 75-grain tablet dissolves readily V V in 8 ounces of water to 'form, av developing solution exhibiting a pH of about 9. Ordinarily film develops therein in 5 minutes at 68 F. p

Example 3, given below-illustrates a one-part developer according to this invention, in the form-of'an' effervescent powder. a a 1 Y The above composition of Example 3 is identical with that of Example 1. The compounding procedure isthe same as set forth under Example 1 except that the tabletting step is omitted. The resulting product is an effervescent powder. 7 I it:

To form a developing solution, '75 "grains. of the eifervescent powder may be dissolved in 8 fluid ouncesaof water. The resulting solution exhibits a pH of about'9, and ordinary film may be developed therein. in 5 minutes Example 4, given below, illustrates another one-part developer according to the'invention, whichin thiscase IS in the form of a non-elfervescent powder.

7 Example 4 Metol (p-methylaminophenol sulfate) I-Iydroquinoire I V 7 2,5 Anhydrous sodium sulfite; .;j 30.0 Sodium carbonate monohydrate; 12,0j Anhydrous sodium acetate.. 45.0

Total 7 '7 1.5

The composition of this example, which contains Ounces avoirdupois.

negatives of very fine grain. By way of illustratiomdcvelopers in accordance with the above examples have been I used to develop Eastman Super XX'35 mm. film in '5 minutes withextremely fine grain, whereas other line grain developers require from 16 to 30 minutes to produce equivalent results.

Developers of this invention exhibit further features 'of photographic excellence, such as the production of excellent shadow detail, and the exhibition of high resolving power.

Developing compositions according to the present invention are highly advantageous in use; In the powder V or tablet form, they exhibit excellent keeping qualities;

and present the advantage of a one-part developer, which,

may be used for the convenient preparation of small quantities-of developing solution. In solution form, the de. velopers also exhibit good keeping qualities. In general,

the developer presents the feature'of economy.

The developer of. this invention maybe utilized advantageously as a one-part developer, in the form of effervescent tablets, effervescent powder, or non-eifervescent powder. Ordinarily there is no advantage in preparing the developer in the form of a non-efiervescent tablet. Certain advantages of the invention may be obtained by preparing the composition as a multi-part developer.

'It will .beiunders tood that variations in the composition of the developer may be made while still coming within the scope of theinvention. Thus, 'various reducing'agents, preservatives and other developer constituents may be employed. The source of sodium acetate may be varied; for example,'sodium diacetate containing 34% acetic acid may be utilized, alone, or in admixture with sodium acetate. I i 7 7 The time of development may also be' varied within the scope of the invention. This may be accomplished by varying the formulation with respect to accelerator or 7 otherwise, or by varying other factors, such as concentration or temperature of solution.

The time of development may also be varied within the scope of the invention.- This may be accomplished by varying the formulation with respect .to accelerator or tration or temperatureof's'olution. V 1

The invention advantageously may be employed in otherwise,.or by varying other factors,'such'as concencolor photography as well as in blaek-and white photography, and may be utilized in the development of .prints as well as of negatives; I V r i i It will be understood that various changes may be made without departing from the invention as herein disslightly over 49% by weight of sodium acetate,'may be prepared 'by mixing together the Metol, hydroquirione and sodium sulfite, and then adding the sodium carbonate and sodium acetate, followed by thorough mixing of:the

entire composition. a

To form a developing solution, 125 grains'oftheaboi e powder may be dissolved in 8 fluid ounces of water, the

resulting solution exhibiting a pH of about 9. At this concentration, ordinary film may be developed in 5 minutesat68"F. V ti.

For the developing offprints,thewconcentratioris'of'the aqueous solutions may be somewhat; greater :than given above. Thus fon print -deyelopment,, the...amounts .of solid developer set to be dissolved in 6 fluid ounces oi water. j: t

'By the present inyention, there islprovided an allpurpose developer, capable of producing film negatives and prints of superior quality.

An outstanding characteristic of the developer is its capability fofdeveloping at high speed, while'producing rth in the specific'examples ma i closed.

Having described my invention, what'l elaim as new and desire to secure by Letters Patent of the United States is a aqueous solution, a silver halide developer, a preservative, sodium carbonate, andsodium acetate in amount from about 20% to about 60% by weight of the solids in said solution, said sodium carbonate being present in sufiicient amount to impart'to said bath a pH of from about 8 to aboutll. p

2. A solid photographic developing composition so1-.

uble in water to produce a developing bath,- said composition comprising a silver halide developer, a preservative, sodium 'carbonate, and sodium acetate in amount from about 20% .to about 60% by weight of said'solid' composition, said sodium carbonate being present in sufficient amount to impart apH of from about 8 to'about;

1 1 to an aqueous developing bath prepared from said composition. I

p 3. A solid photographic developing composition soluble 1. u in Water. to produce a developing 'bath, 'said comp'osition comprising p-methylaminophenol sulfate,jhydroquinone,

sodium sulfite, sodium carbonate, and sodium acetate in amount from about 2.Q% to about 60% by weight of said solid composition, said sodium carbonate being presl. A photographic developing bath comprising, in.

ent in sutncient amount to impart a pH of from about 8 to about 11 to an aqueous photographic developing bath prepared from said composition.

4. A solid, water-soluble, efiervescent, photographic developing composition comprising a silver halide developer, a preservative, sodium carbonate, and sodium diacetate suflicient to provide available sodium acetate in amount from about 20% to about 60% by weight of said composition, said sodium carbonate being present in suflicient amount to produce sodium acetate in solution from the acetic acid content of said sodium diacetate and to impart a pH of from about 8 to about 11 to an aqueous photographic developing bath prepared from said composition.

5. A solid, water-soluble, efiervescent, photographic developing composition comprising a silver halide developer, a preservative, sodium carbonate, and sodium acetate and sodium diacetate together suificient to provide available sodium acetate in amount from about 20% to about 60% by weight of said composition, said sodium carbonate being present in sufficient amount to produce sodium acetate in solution from the acetic acid content of sm'd sodium diacetate and to impart a pH of from about 8 to about 11 to an aqueous photographic developing bath prepared from said composition.

6. A solid, water-soluble, eflervescent, photographic developing composition in the form of a tablet, said tablet comprising a silver halide developer, a preservative, sodium carbonate, and material including sodium diacetate sufficient to provide available sodium acetate in amount from about 20% to about by weight of said tablet, said sodium carbonate being present in sufiicient amount to produce sodium acetate in solution from the acetic acid content of said sodium diacetate and to impart a pH of from about 8 to about 11 to an aqueous photographic developing bath prepared from said composition.

7. A solid, water-soluble, effervescent, photographic developing composition in the form or" a tablet, said tablet containing p-methylaminopheuol sulfate, hydroquinone, sodium sulfite, sodium carbonate, and sodium diacetate sufficient to provide available sodium acetate in amount from about 20% to about 60% by weight of said tablet, said sodium carbonate being present in sufiicient amount to produce sodium acetate in solution from the acetic acid content of said sodium diacetate and to impart a pH of from about 8 to about 11 to an aqueous photographic developing bath prepared from said composition.

References Cited in the file of this patent UNITED STATES PATENTS 1,158,011 Thatcher Oct. 26, 1915 1,990,800 Russell Feb. 12, 1935 2,091,689 Russell Aug. 31, 1937 2,606,118 Rogers Aug. 5, 1952 FOREIGN PATENTS 311,546 Great Britain May 16, 1929 

1. A PHOTOGRAPHIC DEVELOPING BATH COMPRISING, IN AQUEOUS SOLUTION, A SILVER HALIDE DEVELOPER, A PRESERVATIVE, SODIUM CARBONATE, AND SODIUM ACETATE IN AMOUNT FROM ABOUT 20% TO ABOUT 60% BY WEIGHT OF THE SOLIDS IN SAID SOLUTION, SAID SODIUM CARBONATE BEING PRESENT IN SUFFICIENT AMOUNT TO IMPART TO SAID BATH A PH OF FROM ABOUT 8 TO ABOUT
 11. 